Fluid pressure actuated blast gun



Sept. l, 1953 J. E. c. NESHAM AFLUID PRESSURE ACTUATED BLAST -GUN Filed Jan. 15, 1951 Patented Sept. 1, 1953 UNITED STATES TNT OFFICE FLUID PRESSURE ACTUATED BLAST GUN Application January 15, 195i, Serial No. 206,014 In Great Britain January 25, 1950 6 Claims.

This invention relates to a portable fluid pressure actuated blast or jet gun commonly referred to as a percussion blower being used mainly for removing soot from boiler tubes but capable of cleaning purposes generally where a powerful blast is required.

The invention is concerned with that type of blower comprising a casing having a pressure chamber trom which uid pressure, e. g. air or steam, can be discharged in a rapid succession of blasts, by opening and closing a valve leading to a discharge orifice, the valve normally being maintained on its seat by spring bias but being opened by air or other fluid pressure actuated piston to release air from the chamber until the force of the spring is sunicient to overcome the pressure and close the valve, whereupon the same cycle of operations takes place with the result that the gun emits a series of air or other fluid pressure blasts at high speed and pressure.

in practice certain manufacturing difficulties have arisen in the construction of the gun which in the prior art comprises a casing formed in three parts, the intermediate part incorporating the cylinder for the actuating piston.

The seat for the discharge valve is formed on an end part of the casing and it will be appreciated, therefore, that in order to secure a good seat of the discharge valve carried by the piston, it is necessary for the several parts of the casing to be accurately machined. Moreover, should undue wear of the valve or Valve seat take place, it is impossible to regrind the valve seat without upsetting the dimensions so that it is no longer possible for the valve to close against its seating unless shims are removed from between the several parts oi the casing.

The main object of the present invention is to provide an improved design of gun wherein .the outer casing is reduced to a two-part construction, thereby reducing the possibility of leakage of pressure from within the main pressure chamber and enabling manufacturing operations and cost to be reduced owing to the simplicity of construction of the operating parts and the method of assembly. A further object of the in vention is to provide for and simplify any minor adjustments due to wear, such as is liable to take place between the discharge valve and its valve seat, which can be made simply by removal of the valve seat and regrinding in the ordinary manner.

According to the present invention in a fluid pressure actuated blast gun the outer casing is in two parts and includes a cylinder block having a 'the discharge valve closes, both the cylinder block and valve block being detachably secured within the casing.

In the preferred construction the cylinder block is constructed in the form of a spider, the arms of which are machined to t within the casing and provide a direct passage for the pressure fluid from the inlet to the discharge end o1" the casing. ri'he control valve for controlling the admission of air from the pressure chamber within the casing to the piston cylinder may be housed in a duct formed in one of the spider arms.

The casing preferably consists of a cylinder closed at one end and provided at its other end with a detachable screw-on cover plate by means oi which the cylinder block and valve block are secured in position against a shoulder formed in the interior oi the cylinder.

The invention is illustrated in the accompanying drawings, in which:

Figure l is a sectional view of a blast gun constructed in accordance with a preferred embodiment of the invention.

Figure 2 is an end view showing the centre piece and chamber housing the actuating piston oi the gun.

Referring to the drawings, A indicates the outer casing of the gun, in the interior of which is provided a fluid pressure chamber B with an :inlet for admission of nuid, e. g. air or steam,

and provided with a discharge outlet O from which is emitted in rapid succession a series of blasts of air or gas as the case may be at high momentum, the rapid opening and closing of the discharge outlet O being controlled by a discharge valve indicated at V.

Opening and closing movements of the valve V are brought about by a piston P operating in a cylinder indicated at C, the piston P normally being urged to a position wherein the valve V is closed to prevent the escape of pressure from the -casin'g Iiiil.

'be reduced fto a Tminimum.

at one end and provided at its other end with a detachable cap portion IUI so that in effect there is provided a two-part casing with the advantage that leakage losses, which are likely to occur where the casing Iii!) is built up of more than two parts can bereduced 'tblaminimum Referring now to Figures land-12, the barrel portion I is bored at the end opposite to the screw cap IGV to receive a tubular member |02 constituting the inlet nozzle I while the cover plate cap portion IIlI has acentral'orice "Iii to receive a tubular extension -:Hill on a valve block IE5. The block m5 ris internally 2tapered and is provided with a valves'eat 42.

The chamber C within which the actuating piston P reciprocates, may-ask shown be ,cast in one with the block 405, theblocl; m6 being Vin the form of a spider and having conveniently three arms IOT-lill' which are machined at their ends ISS to t ai'counterbore IDS in the The :piston chamber C is closed at its open end'by ascrewfplug'IiIwhich pro 'id'es a seat for `the val-ve Aclosing spring. At its other end chamber C hasv van axialdrilling 4I-SI which `provides aguide forfapiston rod H2 fastwith the piston P and carrying the discharge valve V as 'hereinafter described.

Both the valve `block A-Ii fand piston Vguide block v'IE5 are afmach-ineiit within the counter- Vbore It ofthe casing` I fan-:laresodimensioned as regards their total/'axial 'depth .thatwhen the screwcap IBI is'screw'e'd'home, the two blocks will be held rnily seated *against Vthe interior Yshoulder lffso'fthat a'tight vseal'ican be made by awasher insertedb'etween `the ange of the cap IGI and the block |05.

Thus, vby providing 'casing "iSd- HV in atwo parts and mountingl the -interiorcomponents H15, I G5 within the casing, `manufacturing costs joan "nadd'ition it enables the sealing of the .piston chamberC to be closed by an independentplug If `Withco'nstant Viiuid tightnessof thechamber-'C and no longer is the fluid tightness l:of the apparatus as' a whole dependent-entire' accuratelrnachining Moreover the interior parts can be replacedor renovatedwhen worn.

As shown in Figure `1, theseat 40 for the outlet valve V is provided by a separate .valve block-'lili which enables'the Iseat to 'be-ground independentlyUofthecasing so :that inl the y event of wear, the -blocklcan beiemoved for-grinding. In-order Vtov provider-forreplacement o'r renewal of the valve Vwhichdueto the highfspee'd-oi operation of theg'un is subjected to consider able wear andteanl'the-'piston ro'd I i2 istapered at its end as at I'I3=and the valve V, backed by a reinforcing member IIS', is yforrned'with a corresponding taper'fso that y'it remains' rmlyin place under'the action of the piston and can readily be replaced. `vThisconstruction' also reduces the possibil-ity of shearing 'which'is liable to take placefwhenthevalve'is attached tothe piston rod byscie'wing, lbecauseimmediately the screw works loose the valve will chatter =fan`d break. The inlet valve D, as shown in Figure 1 -is preierablylforndfin the-limb "'I'l ofthe spider `block I 66. 'which-limb is of slightly 'Jincreased Y thicknesstoaccommodatea drilling I2 provided at one -en`d yof =a` tapered-'seat l I2 I for a vsteel l-ball ycomprising the f valve 1D vand wh'lch is urged-against its seat by la spring I-22 held in position by-'ascrew-plug# 23.

duct and said fco'ntrol valve constituting said =meansYfor'controlling the admission oi pressure `ui'dr fromv said chamber to Vsaid cylinder.

r4 ing gland I6 so that an end pressure on the rod hand knob M will unseat the valve D to admit fluid pressure from the interior chamber B past the valve D, whence it iiows through a duct HE into the interior chamber C to cause ja displacement of the piston P against'the spring 1S thus un'seatin'g the valve V'to `.effect a release of the air pressure within the chamber B. Fol- `-lowing the release of pressure, valve V will be moved to its closed position under the action of springs cutting 01T the blast. As soon as the Apreisure in -chamber B has built up the same operation will take place which gives rise to a rapid successionci air or steam or other 'duid .pressure blasts.

It will be appreciated that the spider con- `structionof 'the `block I 36 permits of a direct through iiow of the pressure luid from the inlet I'EiZp'ast `the sector shaped openings between the legs I'I-It and outwardly through the discharge orifice O Without anyfreversal in direction thereby reducing friction and improving the efficiency-oi ythe gun as a whole. Moreover, Itheconstruction of the block: H35 enables it to be die-cast giving a cheaper :manufacture than where a number of holes have to be drilled through an interior block.

I claim:

1. A fluid pressure actuated gun comprising a casing havinglan.interiorrpressure chamber and .being vprovided-at-one -end with an opening for admitting iiuid -under pressure to said chamber, Aa clos-urefmember connected to the opposite end of saidcasinga 'cylinder' block within said chamber, va valve block,1seating ineens within said casing for mounting ,said Ablocks in said casing .one against the other and :said vother against said seatingzmeans,` said-onef'block being engaged bysaid closure member to be held in position thereby, said valve block and said closure meinber having a discharge opening, the valve block being provided withl avalve seat at the discharge opening, a'discharge -valve engageable against Asuch seat yand biased to closed position, said cylinder block having a passage to permit the ilow of duid through said casing fromsaid inlet open- 'ing to said dischargeopening, saidcylinder block having a cylinder therein,va-piston reciprocable infsaid' cylinder and connected to said discharge valve, vandmeans for'controlling the admission of pressure fluid from-said chamber to said cylinder to move said piston and open said discharge valve.

2. The combinationfclaimed in claim l whereinsaid Vcylinderblock is constructed in the form .of aspider `havingarms*mach-ined to lit-within A'said-:casing and to provide said passage for the direct passage of pressure fluid Yfrom the Vinlet 'opening 'to the discharge end' of said casing.

'3. The combination claimed in claim 2 in which-'one ofthe arms yofi-said spider is formed `rwith a duct providing access from saidpressure vchamber to saidcylinder, and a control valve in said-duct for controlling the admission of air fromfsaid pressure 'chamber to saidfcylinder, said f4.-A'fluid pressure -actuatcdiblast gun comprising a casing having an interior pressure chamber, saidcasing-.having an inletv opening at one end for-admitting uid under pressure to said chamber, a closure member for the opposite end of saidy casing, a'fcylinder yblock and a valve block infsaid-casing, fsaidl casing-having a' counterbore providing a shoulder for fixing said blocks in said casing one against the other and said other against said shoulder, said closure member engaging said one block to fix said blocks in said casing, said valve block and said closure member having a discharge opening, the valve block being provided with a valve seat a1; the discharge opening, a discharge valve biased for movement towards said seat, said cylinder block having passages for the flow of pressure iluid from said inlet opening to said discharge valve, said cylinder block having a cylinder, and a piston in said cylinder connected to said discharge valve and operable under pressure in said chamber to open said discharge valve.

5. The combination claimed in claim #i in which said cylinder block is located in said chamber at the end thereof adjacent said closure member, a screw plug closing the end of said cylinder remote from said closure member, and

a spring in said cylinder having its ends respectively engaging said piston and said screw plug.

6. The combination claimed in claim 5 provided With a piston rod connecting said piston to said discharge valve, said piston rod having a tapered end for mounting said discharge valve. JOHN EDWARD CROSSLEY NESHAM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 834,256 Brooks Oct. 3G, 1966 1,087,399 Phelps Feb. 17, 1914 1,234,603 Aylwin July 24, 1917 1,966,854 Eskilson July 17, 193=i 2,361,225 Meyer Oct. 2&1, 19e-4 2,397,871 Kovacs Apr. 2, 1946 2,581,758 Galliano et al Jan. 8, 1952 

